AP Chemistry Unit 3 Review

Which of these molecules could best be represented by the ball-and-stick model shown?

• BeH₂

• CO₂

• H₂O

• SO₂

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NGSS.HS-PS1-3

Which of the following substances contains both ionic and

covalent bonds?

• NH₃

• CH₄

• NaOH

• C₂H₅OH

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NGSS.HS-PS1-3

What type of bonding is found within a water molecule?

• ionic bonding

• polar covalent bonding

• nonpolar covalent bonding

• hydrogen bonding

The Lewis structure of which compound is best represented with resonance structures?

• MgCl₂

• CO₂

• SO₃ ^2-

• OCl₂

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NGSS.HS-PS1-1

The molecule shown above represents alanine, one of the simplest amino acids. This amino acid is considered nonessential to the human diet as it can be synthesized in the body from other compounds.

Which statement is correct concerning alanine?

• Each carbon atom is sp³ hybridized.

• The hybridization of the nitrogen atom is sp².

• All bond angles are approximately 109.50.

• The molecule contains 12 sigma and 6 pi bonds.

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NGSS.HS-LS1-6

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How many unbonded pairs of electrons are found on the alanine molecule?

• 0

• 1

• 3

• 5

Which best describes the bonding in the cyanide ion (CN^-)?

• 3 (sigma) bonds

• 2 (sigma) bonds and I (pi) bond

• 1 (sigma) bond and 2 (pi) bonds

• 3 (pi) bonds

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NGSS.HS-PS1-1

Which bond is the most polar?

• F-O

• H-O

• Na -O

• Sn-O

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NGSS.HS-PS2-4

The effect of lone pairs of electrons on molecular geometry is

• to push other atoms closer together because lone pairs are

  localized on only one nucleus, so they spread out more.

• to allow the other atoms to be further apart because lone pairs

  take up less space than bonding pairs.

• to create an aysmmetical distribution of the electrons within

  the atom, thus creating a polar molecule by creating dipoles.

• to help to create resonance structures through the formation of

  pi bonds.

Why can a molecule with the structure of NBr₅ not exist?

• Nitrogen only has two energy levels and is thus unable to expand its octet.

• Bromine is much larger than nitrogen and cannot be a terminal atom in this molecule

• It is impossible to complete the octets for all six atoms using only valence electrons.

• Nitrogen does not have a low enough electronegativity to be the central atom of this molecule.

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NGSS.HS-PS1-1

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